Abstract: The purpose of the study was to investigate the development of elementary schoolers in two-dimensional spatial transitive inference and analyze the strategies children used during reasoning. At the same time, the mental model theory was examined. The participants were 72 children randomly selected from one middle-level primary school including three groups aged 7, 9 and 11with half boys and half girls in each group. The tests were carried out individually. The methodology of the study was characterized by qualitative and quantitative analyses. The results showed that: (1) Children’s ability of the two-dimensional spatial transitive reasoning increased significantly. The 7-year-olds had begun to bourgeon this kind of reasoning ability, and the 9- and 11-year-olds were in the process of increasing fast; (2) The number of children using the model constructing strategy to resolve problems became more and more with age. Most of the 11-year-olds were able to use it. Even if children had used the model constructing strategy, the difference among task difficulty caused by the number of models isn’t reflected by their reasoning performance; (3) Even if children had used the model constructing strategy, the ability of using this strategy effectively was not high.

Key words: primary school children, two-dimensional spatial transitive reasoning, mental model, strategy